• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.3
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• pp.146-153
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• 2008

High-power communication jammer has to include the switched filter bank to eliminate the harmonic signals generated by amplifier. Generally, the switched filter bank consists of in-out switches and several filters. This paper describes the design of high-power switched filter bank, particularly the high-power filter bank operating over 20$\sim$110MHz frequency range. The filters designed have insertion loss less than 0.3dB, VSWR less than 1.25:1, and harmonic suppression more than 35dB. Also, the switched filter bank can endure upto 2kW high-power signal with very low harmonic level within $30{\mu}s$ switching speed.

• The Journal of the Acoustical Society of Korea
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• v.28 no.8
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• pp.822-831
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• 2009

The porcelain insulators are important devices, that are used to isolate electrically and hold mechanically in the high-voltage power transmission systems. The faults of the insulators induce very serious problems to the power transmission line. In this paper, we introduce techniques for fault detections of insulators by acoustic radiation noises from them. We measured radiation noises from normal state insulators and fault state insulators. The used insulators were two different type porcelain insulators, a cut out switch, two different type line posters, and a lightning arrester. Each results was compared each other in time domain, frequency domain and filter banks' outputs. We found the possibility of detection of insulators' faults and also suggested techniques for fault detections.